In recent years, there is a need to replace a lighting device such as an incandescent bulb which performs dimming by AC phase control from a dimming control device to a light emitting diode (LED) device. However, when the lighting device is changed to an LED device and turned on by the AC phase control from the dimming control device, there is concern that flickering may occur due to the fluctuation of AC voltage or malfunction of the dimming control device due to load. In view of this problem, there is known a technique using an LED device which is an LED device driven by DC power supplied from a dimming control device and turned on at a dimming degree corresponding to a value of a DC voltage.
However, in the above-mentioned LED device, a voltage drop occurs depending on a wiring length between the dimming control device and the LED device or a wiring diameter, the number of the LED devices connected to a wiring, and the like, thus appropriate control is difficult.